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HORIZON_DIST

HORIZON_DIST

Name


      HORIZON_DIST

Purpose


      Compute distance to horizon given observer height.

Category


Calling Sequence


      d = horizon_dist(ht)

Inputs


      h = Observer height. in

Keyword Parameters


Keywords


        /GEOM return geometric horizon, else refracted.
          Perhaps better for large heights.
        /FEET Observer height is in feet, else meters.
        /NMILES Distance is in nautical miles, else km.
        RADIUS=rad Enter Earth radius to use (km, def=6371).
        REFCON=rc Refraction constant (def=7/6).

Outputs


      d = Distance to horizon. out

Common Blocks


Notes


      Notes: Distance is from the observer to the horizon,
        not along the surface. Refraction is approximated
        by using an earth radius of 7/6 times the actual
        earth radius. Refraction is variable but this is
        a typical value and commonly used.
        Ref: http://mintaka.sdsu.edu/GF/explain/atmos_refr/horizon.html

Modification History


      R. Sterner, 2006 Apr 19
  Copyright (C) 2006, Johns Hopkins University/Applied Physics Laboratory
  This software may be used, copied, or redistributed as long as it is not
  sold and this copyright notice is reproduced on each copy made. This
  routine is provided as is without any express or implied warranties
  whatsoever. Other limitations apply as described in the file disclaimer.txt.



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